Gum inhibitor



Patented May 11, 1943 GUM INHIBITOR Albert A. Persyn, Associated, Calif., assignor to Tide Water AssociatedOil Company, San Francisco, Calili, a corporation of Delaware No Drawing. Application February 12, 1940, Serial No. 318,589-

2 Claims.

This invention relates to the prevention or suppression of the formation of gum in cracked, polymerized, and similar gasolines and hastfor a principal object the addition of a particular inhibiting agent to gasolines which normally tend to form gum.

Various means have been employed for the suppression of the formation of gum in cracked gasolines, polymer gasolines, and gasolines obtained from other pyrolytic processes. 10 stance three parts of a gasoline having 60 octane These methods generally consist in adding to rating will require one part of the extract to raise the gasolines small percentages of various subthe octane rating to about 65. stances which apparently have a selective affinity In contradistinction to the use of selective solfor oxygen, thus preventing the oxygen from comvent extracts for increasing the antiknock quality bining with the more reactive constituents of the 1.5 of asolines, the present invention contemplates gasoline to form resinous material, or gum, which the addition of much smaller amounts (less than would form troublesome deposits in various parts 1 in most cases) of the extract to a gasoline of the gasoline engine during use. which is already rather high in antiknock rating. Most inhibitors in general use are somewhat, As cracked gasolines and polymer gasolines norif not readily, soluble in water.v To be entirely zomally have octane ratings of '70 or higher, it will satisfactory as an inhibitor a material should be be r adily appreciated that the addition of from practically water insoluble to prevent its being to of extract, with an octane rating of extracted from the gasoline by any water with about 80, will not appreciably affect the octane which the gasoline may come in contact during rating f he blend. storage. It is, therefore, an object of this inven- It is further to be noted that straight run gasotion to provide an inhibitor which is Water inl s, to which such extracts are customarily mm blended, are gum stable and have no appreciable It has been found that the extract obtained d n y to form gum. It is thus seen that the when treating straight run distillates with a seaddition of the extract to cracked and po m lective solvent such as, for example, with liquid gasolines, which no m y n to f m m, p sulphur dioxide, aniline, acetonitrile, etc. has forms a novel function not contemplated when good gum-inhibiting properties when mixed with t e extract is blended with straight run gasoline. cracked or polymer gasoline. The following are examples of the effective- For this purpose, and according to th invenness of the extract to suppress the formation of tion, there is added to a cracked gasoline, or other gum in cracked and p lymer gasoline: gasoline, which normally would tend to form gum EXAMPLE I in storage, about 5% of a selective solvent extract obtained from astraight run distillate. The par- A mlxture of 111118 parts lleht cracked asoticular percentage added depends upon the l d o e par of polyme gasoline and havamount of inhibiting property desired and may mg a (115131111118 range of to W range from 1% to about 10% or ore, blended with various amounts of a straight run The particular boiling range of the extract is eXtract having a distilling range of about 350 important t has been f und t t higher F. to 4o0 F. The various blends were then testt boiling range t tt is t inhibiting prop ed for stability in accordance with the test deerty. However, too high a boiling range is to be scribed in an article entitled Inhibitors in avoided as this will increase the end boiling point cracked gasoline pu lished in Industrial and of the gasoline depending on the amount used. Engmeenng Chemistry, Volume 24 (1932), pages The preferred boiling range of the extract is be- 1375 to 1382- The method Consists briefly n tween about 350 to 450 F., although 300 F. to sealing a S ple of the gasoline in a steel bomb 500 F. or higher, or lower, may be used. under 100 pounds e pressure of oxy en and Methods for the preparation of the selective h ating for several hours at a temperature of solvent extract are well knowninthe art. Briefly 2 Th len th of time of heating until stated they involve treating a straight run disthere is a sharp reduction in the oxygen pressure tillate with about 100% to 300% by volume of a (due to oxidation reactions in the gasoline) i selective solvent, such as liquid sulphur dioxide caled the "induction period and is generally Such extracts have been used as a means for supplying high anti-knock constituents to an otherwise low octane rating gasoline, such as straight run gasoline. For such purposes rather large quantities of the extract are needed. For inrecognized in .the art to be indicative of stability of the gasoline under test.

the gum Table I shows the induction period of the gasoline with and without extract.

EXAMPLE II A similar blend of cracked and polymer gasolines were blended with straight run extract as before. Table II shows the induction period of the blends.

T able II Octane Induction Blend No. period .Minutes 100% basic gasoline blend 78 45 95% basic gasoline+5% extract 78 240 90% basic gasoline+% extract 78. 5 450 85% basic gasoline+% extract; 78. 5 540 The term gasoline as used herein is intended to mean any fuel suitable for a carbureted internal combustion engine and composed principally of hydrocarbons. The preferred boilin range preferably lies within that commonly used for such purposes, i. e. 80 F. to 437 F. However, cracked gasolines with distillation end points of 350 to 380 F. are commonly used. Gasolines with higher end points than 437 F. may be used.

The term selective solvent extract is used to denote the more aromatic constituents of petroleum which are dissolved in selective solvents of the type exemplified by liquid sulphur dioxide, aniline, and acetonitrile. A number of these solvents are known and used in the art to dissolve and separate the more aromatic constituents of petroleum from the more paraflinic constituents. By far the most suitable of these solvents for the present purposes is liquid sulphur dioxide, due to its low boiling point and consequent ease of separation from the extracted material.

I claim:

1. The process of suppressing the formation of gum in cracked, polymerized, and other pyrolytic gasolines intended for use as fuel for an internal combustion engine and of the type tending to deposit gum during storage, which consists in removing such gum inhibitor compound from straight run petroleum fractions within the boiling range 350-450 F. by treatment with a selective solvent of the type which dissolves the more aromatic hydrocarbons and other compounds, and adding the selective solvent extract to such gasoline in an amount between 2% and 10% of the gasoline, thereby the octane number of the gasoline is not materially altered but the time of formation of gum in the gasoline during storage is greatly lengthened, said extract boiling at temperatures below 450 F. and hence being volatile when carbureted in the internal combustion engine.

2. A motor fuel comprising a cracked gasoline of the type normally tending to deposit gum during storage, and from 2% to 10% of a selective solvent extract from a straight run petroleum distillate within the boiling range 350? 450 F., said extract containing gum inhibiting compounds to delay the formation of gums in cracked gasoline, and being in the boiling range of the cracked gasoline, and said motor fuel having approximately the same octane number as the cracked gasoline alone.

ALBERT A. PERSYN. 

